射孔—酸压—测试三联作(以下简称三联作)射孔爆轰导致井筒环空压力脉动,易造成射孔管柱窜通、断脱等事故。针对这一问题，在射孔爆轰压力脉动理论研究基础上,基于流固耦合理论建立了典型射孔枪—封隔器—套管结构的射孔爆轰井筒压力脉动预测模型;并开展了典型三联作超深井不同井筒环空初始压力、炸药质量、炸药类型对全井筒(封隔器下部井筒)环空压力脉动分布规律及影响研究。结果表明:井筒初始压力在50~125 MPa,炸药质量在15~40 g时,井筒初始压力越高、炸药质量越大,对应的井筒环空压力峰值越大;炸药质量相同时,TNT、HNS、RDX、HMX四种炸药中,RDX炸药造成的井筒环空压力峰值最大。因此,降低井筒初始压力和炸药质量,选用HNS和HMX类型炸药对降低射孔管柱失效风险具有积极意义。研究结果可为三联作射孔作业环空压力安全评估提供参考。

 Due to a triple perforating explosion, the wellbore annulus may experience the pressure fluctuations, potentially causing safety incidents such as channeling and disconnection of the perforating string. A prediction model for the pressure fluctuation in the wellbore annulus during the perforation explosion is established for a typical perforating gun-packer-casing structure. This model is based on fluid-structure coupling theory and theoretical research into pressure fluctuations. The study investigates the distribution of pressure fluctuations and their impact in typical triple-operation ultra-deep wells, taking into account factors such as the initial annular pressure, explosive mass, and type of explosive on the complete wellbore annulus pressure (below the packer). The obtained results indicate that the increased initial wellbore pressure and the increased explosive mass can lead to a higher peak in pressure fluctuation at the wellbore annulus, particularly when the initial wellbore pressure ranges from 50 to 125 MPa, and the explosive mass ranges from 15 to 40 g. Among various explosives such as TNT, HNS, RDX and HMX, RDX has the largest peak pressure fluctuation at the wellbore annulus when the explosive mass is the same. Therefore, the selection of HNS and HMX explosives, along with reduction in the initial wellbore pressure and the explosive mass, can significantly lower the risk of perforating string failure. The results provide reference for annulus pressure evaluation of triple perforating work.